This invention relates to a new and improved floatable pad a plurality of which are useful for providing a substantially gapless insulating cover for floating on a liquid or slurry at a first temperature and which liquid or slurry is exposed to an atmosphere at a second lower temperature and wherein the floating insulating cover is for preventing heat loss by convection from the surface of the liquid or slurry to the atmosphere, liquid loss by evaporation and heat loss by such evaporation.
Such floatable pad and gapless floatable insulating cover are particularly useful for preventing such heat loss and liquid evaporation from a liquid or slurry contained in a device typically referred to in the ore separation art as a thickener, although, as will also be understood by those skilled in the art, the floatable pad and substantially gapless floatable insulating cover of the present invention are not so restricted in their usefulness and such pad and insulating cover may be used in other applications where heat transfer and liquid evaporation are problems.
Referring again to the aforementioned thickener, and as known to those skilled in the ore separation art, a thickener is for increasing the percentage of solids (ground ore) in a slurry of solids and water and for reclaiming water to be recycled and reused in the ore separation process. A typical prior art thickener 10 is illustrated diagrammatically in FIG. 1, and as may be noted from FIG. 1, such thickener is of generally conical horizontal cross-sectional shape and includes an underwater boom 12, mounted rotatably as indicated, and from which boom depends downwardly a plurality of vertical members 14 to the bottom ends of which are attached a plurality of rakes 16 for promoting movement of the solids toward and through the drains indicated diagrammatically by the arrows 18. Typically the slurry input to the thickener 10 is from the top as indicated by the arrows 20 in FIG. 1, although as is further understood by those skilled in the art in some thickeners the input is from the bottom. The thickener 10, in operation, is intentionally filled to overflowing to cause a portion of the water to overflow into the surrounding trough 22 from which the water exits and is recycled for reuse in the ore separation process. As is further known to those skilled in the art, a typical thickener may be approximately 200' in diameter although they can be of different diameters depending upon the particular ore separation process involved.
As if further known to those skilled in the art, water used in the ore separation process (e.g. the ore grinding step), is typically ground water, such as water from an underground well, river, or stream, and hence upon such underground water entering the thickener 10 of FIG. 1, such underground water is typically at a temperature of approximately 55.degree. F. Since many mines in the United States are located in the northern states where the winters are cold, and since most ore separation apparatus are located adjacent the mine for efficiency and reduction of cost associated with transferring ore long distances for ore separation, many thickeners are therefore also located in the northern states where the winters are cold. In the winter months, the temperature of the ambient atmosphere can be, for example, -45.degree. F., and hence a temperature differential of approximately 100.degree. can exist between the temperature of the incoming ground water to the thickener 10 and the temperature of the ambient atmosphere. Typically, as is further known to those skilled in the art, the dwell time of the slurry in a thickener is approximately 40 minutes and with the noted approximately 100.degree. temperature differential, the water can experience significant heat loss through heat transfer to the ambient atmosphere by convection. Since, as noted above, water from the thickener is recycled and reused in the ore separation process, if the water exiting the thickener is greatly reduced in temperature toward the ambient, the water must be reheated at unwanted cost or else the efficiency of the ore separation is reduced since, generally, the higher the temperature of the water in the ore separation process, e.g. the grinding step, the greater the efficiency of the ore separation process.
Still further, and as also known to those skilled in the art, the slurry upon leaving the thickener is further processed in various stages where, for example, the solids (e.g. ground iron ore particles) residing in the exiting water is heated as high as 2,750.degree. F. and since the solids are residing in the water, if the temperature of the water is reduced toward the ambient as described above, the solids residing therein will also be reduced in temperature toward the ambient, and hence greater energy will be required to heat the solids from the ambient to the 2,750.degree. F. temperature than would be required were the temperature of the water to be maintained, or at least substantially maintained, at the above-noted 55.degree. F. temperature.
Accordingly, there exists a need in the art, particularly in the ore separation art with regard to thickeners, for an insulating cover for floating on the liquid or slurry residing in the thickener and for preventing heat loss by transfer of heat to the ambient atmosphere through convection.
As also known to those skilled in the art, particularly the floating insulating cover art, floating insulating covers are known and such prior art floating insulating covers typically comprise a plurality of spherical, sometimes hollow, balls used to cover surfaces of a liquid such as the surface of a typical controlled temperature bath as may be used in acid pickling, plating, rinsing, dyeing, anodizing, phosphating, and food processing in tanks containing liquids, slurries or semi-liquids, maintained at elevated temperatures vis-a-vis the ambient atmosphere. Such prior art floating insulating covers are typically referred to in the art as floating ball blankets and are comprised of generally hollow spherical floatable balls, typically made of plastic, which are reputed to help control the temperature by limiting the surface area exposed to the ambient atmosphere thereby limiting liquid loss or heat loss by heat transfer to the ambient atmosphere by convection from the surface of the covered liquid, slurry, or semi-liquid. As is still further known to those skilled in the floating blanket art, the spherical floatable balls of the prior art, due to their spherical configuration, are engageable only in point-to-point contact and hence provide a floating ball blanket having a plurality of gaps between the spherical floatable balls which gaps leave open space for liquid loss by evaporation, heat loss by such evaporation, and heat loss by heat transfer through convection from the surface of the liquid, etc. Generally, such floatable balls of spherical configuration can cover only approximately 90% of the surface of the liquid, slurry, etc., and as is also known to those skilled in the art, such spherical floatable balls typically float sufficiently high that much less than 90% of the liquid, slurry, etc. surface is in contact with the balls and thus surface evaporation and heat transfer by convection are not curtailed sufficiently as is desired.
Still further, as is also known to those skilled in the art, the spherical shape of the typical prior art floatable ball allows it to roll freely as the liquid is agitated, by being moved or disturbed by the wind, and this rolling action produces an effect similar to the rotating ball of a ballpoint pen, namely, the liquid which wets the bottom of the ball surface is rolled upwardly and exposed to the air and readily evaporates or the heat thereof is readily transferred to the atmosphere and lost through convection.
Accordingly, there exists a need in the art for a floatable insulating cover, comprised of a plurality of individual elements, wherein the elements float in surface-to-surface contact covering the greater portion of the liquid, slurry, semi-liquid or the like, and which provides a more efficient insulation between the liquid, slurry, semi-liquid or the like and the ambient atmosphere.
Still further, as is known to those skilled in the art, particularly the ore processing art including the thickener such as thickener 10 of FIG. 1, the thickener must be drained occasionally for repair purposes and hence for efficiency of repair, and it is desirable that the floating pads or elements of the floating insulating cover be sufficiently rigid to permit a repairman to step on the pad or else the floating pads of the floating insulating cover must be removed from a thickener with the resulting attendant unwanted expense and time loss since a thickener as noted above may be approximately 200' in diameter, a floating element of even 4' in diameter requires approximately 2,500 floating elements to cover a thickener approximately 200' in diameter.
Still further, as is known to those skilled in the art, a thickener exposed to the ambient atmosphere can be exposed to winds, at time high winds, which winds have a tendency to disturb, disrupt and thereby interrupt the floating insulating cover by blowing floating elements away or out of their desired position in surface-to-surface contact. Accordingly, there is a need in the floating insulating cover art of floating elements comprising the cover which float sufficiently low in the liquid, slurry, semi-liquid or the like and which are of sufficient weight to prevent the floating elements from being blown away or the floating insulating cover comprised of such elements to be disturbed and interrupted thereby destroying or greatly reducing the insulating value of the floating cover.
Still further, since as noted above for efficiency the floating elements of the floating insulating cover for covering a large area such as the surface of a thickener are desirably, at least in some embodiments, approximately 4' in diameter, there exists a need for handling such large size floating elements by manual labor.
As noted above, the temperature of the underground water entering the thickener 10 of FIG. 1 is typically at a temperature of approximately 55.degree. F. and in winter months the temperature of the ambient atmosphere or surrounding air can be as low as -45.degree. F., thus a temperature differential of approximately 100.degree. can exist between the temperature of the incoming ground water to the thickener and the temperature of the ambient atmosphere or surrounding air. It has been discovered that, due to this temperature differential, upon a floating insulating cover of a plurality of floating elements covering the liquid, slurry or semi-liquid in a thickener, the lower portion of the floating elements contacting the slurry, etc. tends to expand and the upper portion of the floatable elements contacting the ambient atmosphere or air tends to contract thereby imparting an upwardly bowed, dish-like, or upwardly extending spherical segment configuration, to the floatable elements. This configuration, particularly upon the floating elements being struck by a strong wind, causes the floating elements to slide up on each other forming gaps in the floating cover thereby reducing, and even destroying, the insulating quality of the floating cover thereby permitting unwanted heat and evaporation losses.
Still further, it has been discovered that even where the above-noted temperature differential is not so great and the upwardly bowed configuration of the floating elements is not so pronounced, upon the individual floating elements being of a substantial diameter or transverse width, even a small amount of tilt in a floatable element can cause it to slide up on an adjacent floatable element thereby reducing, and even destroying, the insulating quality of the floating insulating cover.
It has been further found that upon the above-noted upwardly bowed configuration being imparted to the floating elements and coupled with the tendency of the floating elements to tilt particularly when of the noted substantial size, the presence of a strong or powerful wind can cause the floating elements to be blown across the thickener, etc. being covered thereby destroying the insulating quality of the floating cover and even causing loss, damage, or even destruction of the floating elements. Accordingly, there exists a need in the floating insulating cover art for floating element structure for reducing such unwanted tendencies.
As noted above, approximately 2,500 floating elements can be required to cover a thickener of approximately 200' in diameter, and it has been found to be highly desirable to couple a plurality of floating elements together to facilitate their removal from a large body of slurry, etc. and even their removal from a smaller body of liquid such as a typical backyard swimming pool.
Accordingly, there exists a need in the floating element art for coupling means for cheaply and effectively coupling a plurality of floating elements together comprising a floating insulating cover.